1. Field of the Invention
The present invention relates to an α-amylase activity inhibitor containing as an active component polyphenols originating from guava (Psidium guajava Linn.) (hereinafter also called “guava polyphenols”), and to food and beverages containing the inhibitor.
2. Discussion of the Background
Recently, consumers have been keenly conscious of limiting calorie ingestion, because excessive calorie ingestion is a primary cause of adults' diseases attributable to unhealthy habits. However, if there existed substances that could inhibit, or suppress, conversion of ingested food into energy in the living body, such substances would be useful for people in need of dieting, because the substances would allow people to avoid having to reduce their food intake. In particular, inhibiting digestion of carbohydrates led by starch is considered effective for the prevention and therapy of obesity, and therefore, in recent years, substances that inhibit the activity of α-amylase, a digestive enzyme for starch, have become of interest.
Guava is a shrub originating in Central America, and its fruit, roots, and leaves have been used as folk remedies for the treatment of diabetes and diarrhea. According to recent studies, an extract obtained by extracting guava leaves with water or a hydrophilic solvent inhibits α-amylase activity. Japanese Patent Publication (kokoku) No. 60-36746 discloses that the extract can be used as an ingredient of health-promoting beverages, and Japanese Patent Application Laid-Open (kokai) No. 7-59539 discloses that the extract can be used as an ingredient of diet food and beverages.
However, conventional guava extracts also contain sesquiterpene, tannin, and other components, and moreover, their α-amylase inhibitory activity is not necessarily satisfactory for the purpose of achieving desired dieting effect.
Accordingly, an object of the present invention is to isolate from a guava extract a component that exhibits particularly remarkable α-amylase inhibitory activity and thus promises to provide a more effective dieting effect. Another object of the present invention is to provide food and beverages containing the component.